Riveros, signed in May from Mexican side Cruz Azul, has received a work permit but will play for Paraguay against Costa Rica next week before joining up with his new club a couple of days before the season opener against Birmingham.

Sunderland manager Steve Bruce told the club's official website: 'With Cristian going off for international duty it made no sense to bring him over to the UK only for him to fly back to South America.

'By flying Cristian over next week we will get a fresher player as he won't have to make two return trips.

'Cristian has been keeping himself fit and had an excellent World Cup, so I am sure he will be ready to go when he arrives.'